Confined volume coffee aroma

ABSTRACT

A new method of stripping desirable volatiles from roasted coffee has been discovered which does not significantly degrade the quality of the roasted coffee. Roasted coffee is contacted with dry steam in a confined volume at above atmospheric pressures. The pressure is then relieved and the vapors which escape due to the reduction of pressure in the column are condensed to recover aromatic and flavor constituents.

United States Patent RH 1 1 i 1 Inventors William V. White, deceasedlate of Spring Valley, NY. by Grace H. White, heir and executrix;

Claudia L. White and Roger E. White, heirs, Spring Valley, N.Y.; JamesP. Mahlmann, Wayne; Robert P. Stolz,

Dumont, NJ. Appl. No. 849,531 Filed Aug. 12, 1969 Patented Oct. 26, 1971Assignee General Foods Corporation White Plains, N.Y.

CONFINED VOLUME COFFEE AROMA 11 Claims. No Drawings 99/68, 99/71 Int. ClA231l/04 Field of Search 99/65, 68,

[56] References Cited UNITED STATES PATENTS 2,278,473 4/1942 Musher99/65 3,244,531 4/1966 Clinton et al.. 99/71 3,244,532 4/1966 Mahlmann99/71 3,420,674 1/1969 McCartney 99/71 3,421,901 1/1969 Mahlmann et al.99/71 Primary Examiner-Tim R. Miles Assistant Examiner-William L.Mentlik Attorneys-Gerald E. Jacobs, Bruno P. Struzzi and Thomas VSullivan CONFINED VOLUME COFFEE AROMA This application is a continuationin part of copending application Ser. No. 571,382 filed Aug. 10, 1966,now U.S. Pat. No. 3,476,566, entitled Flavor-Improved Process forCoffee."

BACKGROUND OF THE INVENTION This invention relates to a novel method ofstripping desirable volatiles from roasted coffee and collecting thesevolatile materials for further use. More particularly, the inventionconcerns a method wherein undesirable aroma components and gases areremoved from roasted coffee thus improving the quality of lower gradecoffees, also, by carefully controlling conditions, the quality of highgrade coffees is not significantly degraded and the total volatilefraction is found to contain desirable aromatic and flavor constituents.

Prior art processes for steam stripping volatile constituents fromroasted coffee are carried out at atmospheric conditions and undervacuum. The colfee in these processes are exposed to steam treatment forrelatively long periods of time, e.g. 20 minutes and more. This longexposure to steam invariably degrades desirable coffee qualities to anextent whereby the quality of the beverage prepared with the treatedcofiee is inferior to the beverage prepared with untreated coffee.

in U.S. Pat. No. 2,278,473 a method of enhancing coffee beans bysubjecting the coffee to elevated temperatures and pressures andsuddenly releasing the coffee to a lower temperature and pressure isdisclosed. In the aforementioned process the coffee beans are ejectedfrom the chamber in order to disrupt the cell structure of the coffeebean. A very broad range of temperatures and pressures are cited andgenerally the desired upgrading is said to be achieved at pressures offrom 100 to 350 lbs. per square inch and temperatures offrom 300 to 550F.

In copending application Ser. No. 571,382 now Pat. No. 3,476,566 amethod upgrading roasted coffee by the removal of undesirable gases wasclaimed in which the cofi'ee is prewet, allowed to equilibrate at amoisture content of between 4 percent and 40 percent, heated underatmospheric conditions 'such that some of the water is vaporized. Thevaporized water carries with it undesirable volatile constituents fromthe roasted cofiee, thus upgrading the quality of coffee which containshigh amounts of undesirable flavor and aroma volatiles prior totreatment.

SUMMARY OF THE INVENTION This invention is founded on the discovery thatroasted coffee with a moisture content of less than 40 percent can beheated within a narrow temperature range at elevated pressures, within adefined range, for a relatively short time such that not only the flavorof lower quality coffees (e.g. Robustas) can be improved, but thatdesirable volatiles can be liberated from the roasted coffee withoutsignificantly degrading higher quality coffees (e.g. Columbians). Thecoffee is maintained at an elevated pressure by the introduction ofhigh-pressure steam into a pressure vessel. When the pressure in thevessel is released the escaping water vapors carry with them volatilecoffee constituents. It has been found that by carefully controllingcondenser temperatures, a preferred fraction of coffee volatiles can becondensed and collected while less desirable volatiles pass on throughthe condenser system.

As used in this invention roasted coffee includes both the whole roastedbean and ground roasted coffee particles. It has been found that roastedcoffee after being subjected to the process of this invention can befurther treated via normal processes for the manufacture of regularcoffee or soluble coffee. s

The volatiles recovered via the process of this invention can be used toenhance the flavor of coffee extract prior to drying, to enhance theflavor of soluble coffee or as a flavor additive for other foodproducts.

Most unexpectedly, it has been found that while lower grade coffees areupgraded by elimination of undesirable volatile constituents, thecondensed volatiles have desirable flavor characteristics. The coffeetreated via the process of this invention can be further processed foruse as regular coffee or to prepare soluble coffee.

DESCRIPTION OF THE PREFERRED EMBODIMENT Essentially, this inventioninvolves heating roasted coffee at a moisture content of less than 40percent in a confined vessel under pressure. The pressure is built up byintroducing steam into the vessel and isolating the vessel afier apredetermined pressure is achieved. The moisture in the coffee is inintimate contact with the aroma and flavor constituents through thecoffee bean, and when the pressure is relieved by venting, aroma andflavor constituents are carried out of the zone with the escapingvapors. The aromatic and flavor constituents are recovered in acondenser system. It has been found that a preferred moisture level forcoffee to be treated in by process of this invention is about 1 percentto 7 percent by weight of the wetted coffee.

The coffee, at a desired moisture level, is charged into a pressurevessel wherein it is heated by passing steam through the vessel. Thecoffee is heated to a temperature of from 240 to 350 F. The steamdisplaces the air in the vessel which is forced out through a vent line.When the temperature of the exiting gases reaches a predeterminedtemperature, usually below the preferred temperature range for pressuretreatment, the vent line is isolated. This preheating step should beachieved within 5 minutes and preferably in l to 2 minutes. The heatingtime can be controlled by using steam at a sufficiently high pressure toachieve the heating in the desired time.

The pressure in the vessel is then increased to above atmosphericpressure by continuing the flow of steam into the vessel. When thepressure has been increased to a preselected level of from 10 to [00p.s.i.g. the vessel is isolated by closing off the flow of steam. Thecoffee beans are then maintained at the elevated pressure for a periodof from 15 seconds to 10 minutes, preferably 2 to 5 minutes. During thisperiod of time a portion of the water within the beans is vaporized anddisplaces volatile constituents within the coffee bean. The upper limitof 10 minutes is critical in order to avoid significantly degrading theroasted cofiee. Similarly the pressures and temperatures are criticaland a preferred range of pressures is from 20 to 50 p.s.i.g. Thetemperature is maintained at least as high as the temperature ofsaturated steam at the preselected pressure in order to avoid condensingadditional water while the coffee beans are under pressure.

It has been found that under the aforementioned temperature and pressureconditions the moisture in the coffee beans is readily equilibratedthroughout the coffee (whether the beam is in whole or subdivided fonn)so that the moisture can displace, absorb or react with any undesirablevolatiles present in the interior portions. of said cofl'ee. Obviously,the desirable volatile constituents are also in intimate contact withthe equilibrated moisture. The preferred period of contact is from 1 to4 minutes as compared to an equilibration period of from 1 to 2 hourswhich is often necessary under atmospheric conditions.

The vent line is then opened and the water vapors and displaced volatileconstituents of the coffee flow out of the vessel until the pressurewithin the vessel is reduced to atmospheric pressure. It is important tosize the vent line such that the pressure is relieved in a reasonableperiod of time, preferably l to 2 minutes, and at most 5 minutes. Anexcessive time in venting will expose the coffee to undesirableadditional heat treat ment. It is also important to avoid too rapid arelease of pressure. If the gases escape too quickly, it will require animpractically large condenser system to trap and condense the volatileflavor and aroma constituents. Also, too sudden a release of pressurewill result in something like gun-puffing or an explosion of the coffeeand this is to be avoided. The escaping water vapors and coffeevolatiles are passed through a condenser system wherein the volatilesare condensed and collected. For the purpose of this invention, thevessel is considered to have reached atmospheric pressure when a gage atthe top of the vessel indicates atmospheric pressure. It is understoodthat there may be a pressure gradient remaining from top to bottom ofthe vessel. The process does not require waiting for the pressurethroughout the column to reach atmospheric conditions.

Unexpectedly, it has been found that the steam treatment under pressurenot only drives off what would be undesirable volatile constituents, ifsaid constituents were to remain in the coffee, but apparentlychemically changes the makeup of these undesirable volatiles such thatall of the volatiles collected in the condensate system have desirablecoffee characteristics. Thus, the so called undesirable volatiles arecondensed and collected together with normally desirable volatiles toyield a valuable, flavor enhanced, condensate.

It has been found that the condenser temperature should be maintained ata maximum of about 100 F. If higher temperatures are used a desiredfraction of the volatile material will pass on through the condensersystem and the resultant condensate will have a weak or thin character.The condenser temperature can be as cold as desired and liquid nitrogenhas been used as a cooling medium for some experimental work. Apreferred range of condensate temperatures is from 30 to 90 F. and themost preferred range is from 50 to 75 F.

While the coffee beans are still in the vessel the steam strippingprocess of this invention can be followed by purging the vessel andcoffee with an inert gas, preferably nitrogen. It has been found thatthe inert gas will pick up and carry out of the vessel additional coffeevolatiles which can be condensed and added to the volatile fractionalready collected with the condensed water vapors. The volatiles comingoff with the nitrogen can be separated into fractions by collecting apredetermined volume of additional volatiles based upon the weight ofcoffee in the vessel and the geometry of the system. Successivefractions of volatiles have been found to have distinct flavorcharacteristics and a given fraction may be more desirable for somespecific applications than the combined condensate.

It has been found that the steam treatment can be shortened bypreheating the pressure vessel prior to charging the coffee into thevessel. The walls of the vessel are preheated to at least thetemperature to be maintained during the period in which the beans areisolated under pressure. In order to avoid unnecessary degradation ofthe coffee beans it is desirable to complete the process of thisinvention, from the point wherein steam is introduced to the vessel tothe point in the process wherein the pressure in the vessel after beingraised is again reduced to atmospheric pressure, in a total time notexceeding minutes. It has also been found that a preferred period oftime wherein the beans are maintained at the elevated pressure is from ito 4 minutes when using pressure of from to 50 p.s.i.g.

It has been found that as an alternative to building up the pressurewith steam, the pressure can be achieved by heating an isolated vesselcontaining coffee and sufficient added water, such that when the addedwater is vaporized the desired pressure will be build up. Thus, coffeecan be charged into an autoclave. Water is added to the autoclave. Theautoclave is isolated and heated externally to vaporize the water andthe coffee is maintained in contact with the vapors for from 1 to 10minutes. The pressure is then relieved by venting the autoclave toatmospheric pressure and the escaping gases are passed through acondenser system.

The following examples will further describe the process of thisinvention:

Example 1 One hundred and five pounds of roasted coffee beans at amoisture content of 7 percent were charged into a stainless steelinsulated column (8 inches diameter by 14 feet) which had been preheatedto a temperature of 350 F. Steam at 40 p.s.i.g. was fed into the bottomof the column to heat the beans and flush out the air through a ventline at the top of the column. After 1% minutes the gases exiting fromthe vent line had a temperature of about 240 F. and the vent valve wasclosed. The pressure in the column was raised to 30 p.s.i.g. bycontinuing to feed steam into the column for about 1 minute. The columnwas then isolated by closing off the steam line and the coffee wasmaintained under pressure for 2 minutes. The top vent valve was thenopened and the volatile coffee constituents and water vapor allowed topass into a condenser which was maintained at 45 F. with chilling water.The flow of vapors continued for 2 minutes before the pressure in thecolumn was reduced to atmospheric pressure and 750 ml. of condensate wascollected at a temperature of from 75 to 65 F. as it came out of thecondenser.

The charged cofi'ees were a blend of Columbians and Robustas. A brew ofthe treated coffee was prepared and the resultant brew was found to bericher and had a more desirable flavor then a brew similarly preparedwith the same blend of coffees which had not been subjected to theprocess of this invention. Thus, there is proof that the upgradingassociated with the process of this invention was achieved. Also theflavor of the Columbian coffee was not significantly degraded. Inaddition to improving the flavor of the brew it was found that theclarity of the brew prepared from the treated cofiee was improved.

The condensate was found to contain a blend of desirable coffee flavornotes.

Example ll Coffee treated as in example 1 was extracted in a typicalsoluble coffee extraction process. The condensed volatiles obtained inexample I were added to the extract prior to spray drying the extract.The resultant soluble coffee was significantly enhanced and consideredsuperior to a similar soluble coffee prepared without the addition ofcondensed volatiles.

Example Ill The process of example I was prepared. After the pressure inthe column had been reduced to atmospheric pressure nitrogen gas waspassed through the coffee in the column. Seven hundred fifty millilitersof condensate containing additional volatiles was collected from thecondenser in 1 minute. These volatiles were added to the 750 ml. ofcondensate originally collected and it was found that the additionalvolatiles added desirable coffee notes to the condensate not previouslydetected.

Similarly, a third fraction of volatiles was collected by continuing thenitrogen flush and condensation technique for another minute. Onceagain, the additional condensate added new and desirable coffee notes tothe condensate.

Example IV A cylindrical pressure vessel having a height of 13 feet anda width of 10 inches was preheated prior to introduction of the coffeecharge by injecting steam into the closed vessel for about 10 minutesuntil the temperature of the vessel walls reached 350 F. The vessel wasthen opened and vented to atmosphere. A l00-pound charge of roastedRobusta coffee (lndonesian variety having a normal roasted color andground to a particle size wherein 97 percent of the coffee was retainedon a 40-mesh U.S. Standard Screen and having a moisture content of 20percent was placed inside the vessel. The vessel was isolated except fora vent valve at the top. Steam at 50 p.s.i.g. was passed through thecoffee for 1 minute to heat the coffee and purge entrapped air. The ventvalve was then closed and steaming was continued until a pressure of 35p.s.i.g. was developed in the vessel. The steam flow was then shut offand the coffee maintained at an elevated temperature and pressure for 2minutes. The vessel was vented and the escaping vapors were passed overa condenser similar to that used in example I.

The Robusta coffee was found to have been upgraded, as evidenced by amore desirable brew then that obtained from the equivalent coffee whichwas not treated.

The condensate was found to have desirable coffee notes which enhancedthe flavor of soluble coffee when added thereto. While this inventionhas been described by reference to several specific examples, it isunderstood to be limited only by the scope of the appended claims.

What is claimed is:

l. A process for separating and collecting desirable coffee volatilesfrom roasted coffee comprising placing roasted coffee in a vessel, saidroasted coffee having a moisture content of from 1 to 40 percent byweight, passing steam into said vessel through a steam inlet line thusheating the roasted coffee to a temperature of from 240 to 350 F. anddisplacing gases in the vessel, said gases being forced out a vent line,closing said vent line when the exiting gases are at a predeterminedtemperature, continuing to pass steam into the vessel until the pressurewithin the vessel is increased to a level of from to 100 p.s.i.g., thetemperature of the coffee having been heated to a temperature at leastequivalent to the temperature of saturated steam at the elevatedpressure, closing oh the steam inlet line thus isolating the vessel atthe elevated pressure, maintaining the roasted coffee under pressure forfrom seconds to 10 minutes, opening said vent line thus allowing watervapors to flow out of the vessel until the pressure in the vessel isreduced to atmospheric pressure, said water vapor carrying along coffeevolatiles liberated from the roasted coffee, condensing a fraction ofthe coffee volatiles and water vapor at temperatures of from -l00 F. toa maximum of 100 F. such that a maximum condensate temperature of 100 F.is achieved and collecting said condensate.

2. The process of claim 1 wherein the total elapsed time from the timethe steam is first introduced into the vessel to the time the vessel isreturned to atmospheric pressure is less than 15 minutes.

3. The process of claim 2 wherein the pressure within the vessel israised to a pressure of from to 50 p.s.i.g. and is maintained at saidpressure for from 1 to 4 minutes prior to opening the vent line.

4. The process of claim 3 wherein the condensate is at from 35 to 90 F.

5. The process of claim 3 wherein the condensate is at from 50 to 75 F.

6. The process of claim 1 wherein an inert gas is blown through thevessel after it is at atmospheric pressure, said inert gas sweeping outadditional coffee volatiles, condensing said additional volatiles andcombining the additional condensed volatiles with the initial volatilescarried out with the water vapors.

7. The process of claim I wherein the vessel is preheated prior tointroduction of steam into the column, the temperature of the vesselbeing raised to at least the temperature of saturated steam at thepressure to be maintained when the vessel is isolated at aboveatmospheric pressure.

8. The process of claim 4 wherein an inert gas is blown through thevessel after it is at atmospheric pressure, said inert gas sweeping outadditional coffee volatiles, condensing said additional volatiles andcombining the additional condensed volatiles with the initial volatilescarried out with the water vapors.

9. A process for upgrading roasted coffee having a high amount ofundesirable flavor and aroma constituents comprising placing roastedcofiee in a vessel, said roasted coffee having a moisture content offrom i to 40 percent by weight, passing steam into said vessel through asteam inlet line thus heatin the roasted coffee to a temperature of from240 to 350 and displacing gases in the vessel, said gases being forcedout a vent line, closing said vent line when the exiting gases are at apredetermined temperature, continuing to pass steam into the vesseluntil the pressure within the vessel is increased to a level of from 10to p.s.i.g., the temperature of the coffee having been heated to atemperature at least equivalent to the temperature of saturated steam atthe elevated pressure, closing off the steam inlet line thus isolatingthe vessel at the elevated pressure, maintaining the roasted coffeeunder pressure for from 15 seconds to 10 minutes, opening said vent linethus allowing water vapors to flow out of the vessel until the pressurein the vessel is reduced to atmospheric pressure, said water vaporcarrying along coffee volatiles liberated from the roasted coffee.

10. The process of claim 9 wherein the total elapsed time from the timethe steam is first introduced into the vessel to the time the vessel isreturned to atmospheric pressure is less than 15 minutes.

11. The process of claim 10 wherein the pressure within the vessel israised to a pressure of from 20 to 50 p.s.i.g. and is maintained at saidpressure for from i to 4 minutes prior to opening the vent line.

2. The process of claim 1 wherein the total elapsed time from the timethe steam is first introDuced into the vessel to the time the vessel isreturned to atmospheric pressure is less than 15 minutes.
 3. The processof claim 2 wherein the pressure within the vessel is raised to apressure of from 20 to 50 p.s.i.g. and is maintained at said pressurefor from 1 to 4 minutes prior to opening the vent line.
 4. The processof claim 3 wherein the condensate is at from 35* to 90* F.
 5. Theprocess of claim 3 wherein the condensate is at from 50* to 75* F. 6.The process of claim 1 wherein an inert gas is blown through the vesselafter it is at atmospheric pressure, said inert gas sweeping outadditional coffee volatiles, condensing said additional volatiles andcombining the additional condensed volatiles with the initial volatilescarried out with the water vapors.
 7. The process of claim 1 wherein thevessel is preheated prior to introduction of steam into the column, thetemperature of the vessel being raised to at least the temperature ofsaturated steam at the pressure to be maintained when the vessel isisolated at above atmospheric pressure.
 8. The process of claim 4wherein an inert gas is blown through the vessel after it is atatmospheric pressure, said inert gas sweeping out additional coffeevolatiles, condensing said additional volatiles and combining theadditional condensed volatiles with the initial volatiles carried outwith the water vapors.
 9. A process for upgrading roasted coffee havinga high amount of undesirable flavor and aroma constituents comprisingplacing roasted coffee in a vessel, said roasted coffee having amoisture content of from 1 to 40 percent by weight, passing steam intosaid vessel through a steam inlet line thus heating the roasted coffeeto a temperature of from 240* to 350* F. and displacing gases in thevessel, said gases being forced out a vent line, closing said vent linewhen the exiting gases are at a predetermined temperature, continuing topass steam into the vessel until the pressure within the vessel isincreased to a level of from 10 to 100 p.s.i.g., the temperature of thecoffee having been heated to a temperature at least equivalent to thetemperature of saturated steam at the elevated pressure, closing off thesteam inlet line thus isolating the vessel at the elevated pressure,maintaining the roasted coffee under pressure for from 15 seconds to 10minutes, opening said vent line thus allowing water vapors to flow outof the vessel until the pressure in the vessel is reduced to atmosphericpressure, said water vapor carrying along coffee volatiles liberatedfrom the roasted coffee.
 10. The process of claim 9 wherein the totalelapsed time from the time the steam is first introduced into the vesselto the time the vessel is returned to atmospheric pressure is less than15 minutes.
 11. The process of claim 10 wherein the pressure within thevessel is raised to a pressure of from 20 to 50 p.s.i.g. and ismaintained at said pressure for from 1 to 4 minutes prior to opening thevent line.